Conveyor for mixed freight handling system

ABSTRACT

A mixed freight handling system, particularly for limited access areas such as an end-opening trailer at a dock, includes a telescoping conveyor overlapping a fixed conveyor and translatable into the trailer to receive hand liftable articles. A freight manipulator includes an appropriate and changeable freight manipulator tool mounted on an extendible boom and is translatable adjacent and along the conveyors to the dock edge. The tool is extendible into the trailer for engaging and supporting manually nonliftable freight for transfer to or from a freight conveyor extending alongside the path of the manipulator. The telescoping conveyor includes a base section engaged with a track, an inclinable lift section, and a liftable and laterally swingable head section. The manipulator includes a chassis engaged with a track straddling the fixed and telescoping conveyors and has a tunnel formed therethrough, allowing the passage of articles on the conveyors therebeneath. The extendible boom is attached to the chassis and is supported at an outer end by a wheeled bogie. The telescoping conveyor and manipulator cooperate in such a manner that the manipulator can be extended into the trailer without retraction of the telescoping conveyor.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 07/280,720, filed Dec. 6,1988, now U.S. Pat. No. 5,009,560.

FIELD OF THE INVENTION

The present invention relates to article shipping and handling systemsand, more particularly, to a mixed freight handling system fortransferring a mixed load of hand liftable articles and heavy or bulkyfreight between a truck trailer and a dock.

BACKGROUND OF THE INVENTION

There are many systems available and in use for efficiently loading andunloading truck trailers with relatively uniform types of freight. Forexample, if a trailer is loaded only with hand liftable cartons, thetrailer may be unloaded entirely manually, as onto pallets on a dock; ora conveyor may be extended into the trailer, and the cartons manuallyplaced on the conveyor. Similarly, if a trailer is loaded only withpalleted freight, it may be unloaded fairly efficiently using aconventional fork lift truck.

In some trucking operations, particularly larger general freightcarriers, a great variety of freight may be shipped from a number ofdiverse origins to a central facility for local or distanttransshipment. At the central facility, freight from the arriving trucksis unloaded, sorted according to destination, then reassembled intoloads in such a manner as to most economically utilize the trucks.Because of the nature of this kind of shipping operation, trucks oftenarrive at a central facility with mixed freight loads, hand liftablearticles interspersed with palleted freight and other types of bulky orheavy articles which are not suitable for manual unloading. Such mixedfreight loads are often referred to as "LTL" freight for "Less (than)Truck Load".

In the past, the utilization of labor and equipment in unloading suchLTL trailers has often been inefficient and uneconomical. Because of theindeterminate mix of manually liftable freight and freight requiringmechanized handling and the uncertainty of arrival times of trucks, itis often difficult to provide an optimum combination of labor andequipment to assure that the laborers are not overworked at certaintimes and left idle at others. On some docks, only certain designatedpersons may be permitted to operate fork lift trucks, for reasons ofsafety or labor contract requirements. Also, a single fork lift truck orconveyor may be required to service multiple dock positions. Asdifferent types of freight are encountered in unloading the trailer,workers are often left standing about idly as equipment is awaited andchangeover thereof occurs. If unloading conveyors are employed in thetrailers to receive manually liftable articles, time and effort areconsumed in extending and retracting the conveyors as different types offreight are encountered.

In loading truck trailers with mixed types of freight for offloading atseveral locations, it is desirable to position the freight in such amanner as to minimize handling at each stop. Thus, a load for a firststop is positioned rearmost in the trailer, and a load for a last stopis positioned toward the front of the trailer. Problems similar to thoseencountered in unloading mixed freight occur in loading mixed freightonto trailers.

The results of such inefficiency, among other disadvantages, are thatdock workers and unloading equipment are inefficiently employed and thedocks and truck trailers are tied up awaiting loading or unloading.Shipping costs are thereby increased and profits to the warehousingfacility and/or trucking company are diminished.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus to overcome many ofthe problems associated with the conventional manner of handling mixedloads of freight. The present invention is particularly directed tounloading mixed freight. However, with the disclosed structure orappropriate modifications thereof, the methods and apparatus describedbelow are also applicable to loading mixed freight. In general, thepresent invention combines a conveyor extendible into a trailer toreceive hand liftable articles with a freight manipulator extendibleinto the trailer without removal of the conveyor to engage and unloadfreight which is not hand liftable.

The extendible conveyor preferably includes a rear base section, amiddle lift section, and a front head section and is supported bysurface engaging wheels which ride on conveyor support rails on the dockfloor and on the bed of a trailer when extended. The base section isengaged with guide tracks which run parallel to the support rails. Theextendible conveyor overlaps a fixed conveyor to which articles arecommunicated or transferred by the extendible conveyor. The lift sectionis pivotally connected to the base section for pivoting about a lateralaxis. The head section includes a pitch frame connected to the liftsection for pivoting about a lateral axis or pitching and a swing frameconnected to the pitch frame for pivoting about a vertical axis orswinging. Lift struts are pivotally connected to a front end of the liftsection, and hydraulic lift cylinders are pivotally connected betweenthe struts and the pitch frame of the head section. Leveling links arepivotally connected between inner ends of the struts and the sides ofthe pitch frame such that when the cylinders are extended to lift thehead section, the links cause the head section to remain substantiallylevel. The sections of the extendible conveyor are provided with endlessconveyor belts which are independently driven by motors mounted in therespective sections.

The extendible conveyor is translated or telescoped along the supportrails by a motor drivingly engaged with drive wheels mounted on the basesection. The lift and head sections are extendible up to and into atrailer parked at the dock. The extendible conveyor is adapted toreceive hand liftable articles, such as cartons, from the trailer andconvey them to the fixed conveyor which may communicate with anotherconveyor such as a sorting conveyor system, an accumulation conveyor, orthe like. The raisable head section facilitates unloading articles whichare stacked on other freight such that a worker is usually not requiredto actually lift articles, only "swing" them onto the head section. Theability of the head section to swing to the right or left facilitatesunloading articles positioned in the trailer off the center line.

The freight manipulator includes a translatable chassis mounted ontracks parallel to and outside of the guide tracks of the extendible ortelescoping conveyor and a boom, preferably extendible, having a freightengaging tool mounted on a front end thereof. The chassis is shapedinternally to form a tunnel through which the fixed and extendibleconveyors are directed. This feature allows articles to be conveyed onthese conveyors through the manipulator chassis and allows the toolcarriage of the manipulator to be extended into a trailer over thelowered head section of the conveyor without retraction thereof. Thechassis is supported by rimmed wheels on rails which may be the samerails which guide the extendible conveyor. The chassis wheels arejournaled on chassis legs which are spaced apart to straddle theextendible and fixed conveyors when passing thereover. The chassis isself propelled by a motor arrangement drivingly engaged with chassiswheels and can be translated up to near the edge of the dock to extendthe boom into the open end of a trailer parked at the dock. The boom ispositioned to cause the tool carriage to engage freight therein.

The boom, in one form, is comprised of telescoping sections including anouter rear section attached to the chassis, a middle section sleevedwithin the rear section, and an inner front section sleeved within themiddle section. A pair of hydraulic middle section extension cylindersare connected between the middle and rear sections of the boom and arepositioned external to the rear and middle sections. A hydraulic frontsection extension cylinder is connected between the middle section andthe front section and is positioned within the middle and front section.The front section has a tool support carriage base at a front endthereof. A tool support carriage is connected to the carriage base bytool articulation means such that the tool carriage is liftable andlowerable with respect the carriage base, pivotable about a verticalaxis from left 180 degrees around to right, shiftable laterally, andtiltable fore and aft to a small degree. The carriage base is supportedby a wheeled bogie which is extendible and retractable a short distanceto accommodate trailer beds which are not precisely coplanar with thedock floor and which might rise as the trailer is unloaded. A variety offreight manipulating tools are attachable to the tool support carriage,such as fork extensions, a rug pole, drum clamps, jib boom, etc.

A freight or manipulator conveyor is positioned alongside themanipulator track and is adapted to receive freight removed from thetrailer by the manipulator. The lateral shifting feature of the toolcarriage allows freight on the sides of the trailer to be engaged andlifted using the lift feature. The pivoting feature of the tool carriageallows the freight to be deposited onto the freight conveyor. In aloading situation, the freight is removed from the freight conveyor andplaced in the trailer by the manipulator.

The manipulator preferably has its own hydraulic pump driven byelectrical power transmitted to the manipulator by way of a power railextending alongside the path of the manipulator. A system of reels onthe manipulator pays out hydraulic hoses to the internal extensioncylinder and to the cylinders which articulate the tool supportcarriage. In a preferred form, the manipulator is adapted toautomatically execute a number of functions, such as parking in a fullyretracted condition, retraction of the boom and placement of a load onthe manipulator conveyor, and the changeover of freight engaging tools.

The extendible conveyor and freight manipulator cooperate to allowefficient unloading and loading of a trailer. The extendible conveyor isextended along the fixed conveyor into the trailer to receive and conveyhand liftable articles. When a palleted load of freight or othermanually nonliftable freight is encountered, the extendible conveyor maybe lowered, if necessary; and the freight manipulator controlled toextend the manipulator tool into the trailer over the lowered extendibleconveyor to engage the freight. It is not necessary to retract theextendible conveyor to allow entry of the manipulator tool supportcarriage and boom support bogie into the trailer. Articles still on theextendible and fixed conveyors are not disturbed but merely conveyedthrough the manipulator chassis tunnel. When the freight has beenengaged, the freight manipulator is controlled to automatically retractthe boom and translate the manipulator chassis to an appropriateposition to place the freight on the freight conveyor and park itself.Meanwhile, a worker may resume placing hand liftable articles onto thetelescoping conveyor as the manipulator withdraws.

OBJECTS OF THE INVENTION

The principal objects of the present invention are: to provide animproved system for unloading mixed freight from truck trailers; toprovide such a system including an extendible or telescoping conveyorwhich is translatable into a trailer for conveying manually liftablearticles; to provide such a system with an independently translatablefreight manipulator with a chassis straddling the conveyor andtranslatable to the edge of a dock to extend a freight lift member suchas fork tines into the trailer to engage nonmanually liftable freight,such as palleted loads and the like; to provide such a system whereinthe extendible conveyor overlaps and communicates with a fixed conveyor;to provide such a system wherein the extendible conveyor includes a headsection connected by an inclinable lift section to a base section, thehead section being liftable to facilitate unloading of stacked articlesand swivelable to facilitate unloading articles positioned laterallywithin the trailer; to provide such a system wherein the head section ofthe extendible conveyor includes a collapsible worker platform to lift aworker to facilitate reaching stacked articles within the trailer; toprovide such a system wherein a telescoping conveyor is positioned on aconveyor track extending to near the edge of the dock, the conveyorbeing supported on wheels which engage the bed of the trailer within thetrailer; to provide such a system wherein the manipulator chassis ismounted on manipulator tracks parallel to and outside of the conveyortracks and has a tunnel therethrough for passage of articles on thetelescoping and fixed conveyors through the chassis and for independenttranslation of the manipulator relative to the telescoping conveyor; toprovide such a system wherein the manipulator includes a tool carriageconnected to the chassis by an extendible boom and supported by awheeled bogie which allows a freight engaging tool to be extended to thefront end of a standard size trailer; to provide such a system wherein avariety of freight engaging tools, such as fork tines and extensions, adrum clamp, a rug pole, jib boom, or the like, are interchangeablyconnectable to the tool carriage for handling a variety of types offreight; to provide such a system wherein the tool carriage is capableof a wide range of articulation, such as lateral shifting to engagefreight positioned on the extreme sides of a trailer, pivoting throughat least 180 degrees about a vertical axis, tilting, and the like; toprovide such a system including a freight conveyor extending alongbeside the manipulator tracks to receive freight from the manipulator;to provide such a system wherein the manipulator is programmed forcertain automatic functions such as the translation of the chassis tothe extremities of the manipulator tracks, the retraction of the boomand translation of the manipulator to a position to set off a unit offreight onto the freight conveyor, the interchanging of freight engagingtools, parking of the manipulator, and the like; to provide such asystem wherein the telescoping conveyor in an extended and loweredcondition may remain in the trailer without interference as the toolcarriage of the manipulator is extended into the trailer to engage aunit of nonmanually liftable freight; to provide such a system which canbe operated by a single worker to unload a trailer; to provide such asystem which with or without appropriate modifications may be used toload trailers; and to provide such a mixed freight handling system whichis economical to manufacture, efficient and convenient in operation, andwhich is particularly well adapted for its intended purpose.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification, include exemplaryembodiments of the present invention, and illustrate various objects andfeatures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a plurality of the mixed freighthandling systems embodying the present invention installed at a truckdock.

FIG. 2 is a rear elevational view of a freight manipulator of the mixedfreight handling system and a power rail which provides electrical powertherefor.

FIG. 3 is a side elevational view of a telescoping conveyor, freightmanipulator, and fixed conveyor of the mixed freight handling systemaccording to the present invention.

FIG. 4 is a fragmentary top plan view taken on line 4--4 of FIG. 3 andillustrates a fixed conveyor and rails for the telescoping conveyor andthe freight manipulator of the mixed freight handling system.

FIG. 5 is an enlarged fragmentary longitudinal sectional view taken online 5--5 of FIG. 4 and illustrates details of the fixed conveyor of thesystem.

FIG. 6 is a fragmentary side elevational view of the telescopingconveyor and freight manipulator of the present invention shown insimultaneous presence within a truck trailer at a dock.

FIG. 7 is an enlarged fragmentary side elevational view of a trackengaging wheel and anti-tipping rollers of the freight manipulator ofthe present invention.

FIG. 8 is an enlarged fragmentary transverse sectional view taken online 8--8 of FIG. 7 and illustrates further details of a track engagingwheel and an anti-tipping roller of the freight manipulator.

FIG. 9 is an enlarged fragmentary rear end elevational view taken online 9--9 of FIG. 6 and illustrates details of a drive wheel of thefreight manipulator.

FIG. 10 is a greatly enlarged, fragmentary transverse sectional viewtaken on line 10--10 of FIG. 4 and illustrates details of support railsand guide tracks for the telescoping conveyor and the freightmanipulator and details of the telescoping conveyor and fixed conveyor.

FIG. 11 is a fragmentary side elevational view of a base section, a liftsection, and a head section of the telescoping conveyor illustrated in alowered condition.

FIG. 12 is a view similar to FIG. 11 and illustrates the lift sectionand head section of the telescoping conveyor in a lifted condition.

FIG. 13 is a fragmentary top plan view of the head section of thetelescoping conveyor with a portion broken away to illustrate details ofa head section swinging mechanism.

FIG. 14 is a fragmentary view similar to FIG. 13 and illustrates thehead section of the telescoping conveyor pivoted to the left, as viewedtoward a front end thereof, and with the head section pivoted to theright diagrammatically illustrated in phantom lines.

FIG. 15 is an enlarged fragmentary top plan view of the base section ofthe telescoping conveyor with portions broken away to illustrateoperational details thereof.

FIG. 16 is an enlarged fragmentary top plan view of the lift section ofthe telescoping conveyor with portions broken away to illustrateoperational details thereof.

FIG. 17 is a greatly enlarged fragmentary top plan view illustratingdetails of a pivotal joint between the base section and the lift sectionof the telescoping conveyor.

FIG. 18 is an enlarged fragmentary side elevational view of a front endof the lift section and a rear end of the head section of thetelescoping conveyor and illustrates details of a swinging pivotal jointbetween a pitch frame of the head section and a swing frame thereof.

FIG. 19 is a greatly enlarged fragmentary top plan view taken on line19--19 of FIG. 18 and illustrates a pivotal joint between the liftsection and the head section of the telescoping conveyor.

FIG. 20 is an enlarged fragmentary longitudinal sectional view taken online 20--20 of FIG. 16 and illustrates internal operational details ofthe lift section of the telescoping conveyor.

FIG. 21 is an enlarged fragmentary longitudinal sectional view taken online 21--21 of FIG. 15 and illustrates internal operational details ofthe base section of the telescoping conveyor.

FIG. 22 is a further enlarged fragmentary side elevational view of thehead section of the telescoping conveyor with portions broken away toillustrate internal details thereof.

FIG. 23 is a fragmentary top plan view of the head section of thetelescoping conveyor at a scale similar to FIG. 22, with portions brokenaway to illustrate details of the swinging mechanism and belt drivemechanisms thereof.

FIG. 24 is a fragmentary top plan view of a boom of the freightmanipulator shown in an extended condition with phantom viewsillustrating lateral shifting positions of a tool carriage thereof andwith phantom views in a retracted condition of the boom illustratingright and left pivoting extremes of the tool carriage.

FIG. 25 is a side elevational view of the freight manipulator with asomewhat extended condition of the boom shown in phantom.

FIG. 26 is an enlarged fragmentary side elevational view of a chassis ofthe freight manipulator and illustrates details of reels for paying outand retracting hydraulic hoses supplying operational components of themanipulator.

FIG. 27 is a diagrammatic fragmentary longitudinal sectional view of theboom of the freight manipulator in a retracted condition and illustratesan internal hydraulic cylinder thereof for extending and retracting aforward section of the boom.

FIG. 28 is a diagrammatic fragmentary longitudinal sectional view inplan of the boom of the freight manipulator in a retracted condition andillustrates external hydraulic cylinders thereof for extending andretracting an intermediate section of the boom.

FIG. 29 is a greatly enlarged fragmentary transverse sectional viewtaken on line 29--29 of FIG. 28 and illustrates details of the boom ofthe freight manipulator.

FIG. 30 is an enlarged fragmentary side elevational view of the boom ofthe freight manipulator and illustrates details of a boom support bogiewith portions broken away and with raised and lowered positions of thebogie illustrated fragmentarily in phantom.

FIG. 31 is a fragmentary transverse sectional view taken on line 31--31of FIG. 30 and illustrates details of the boom support bogie of thefreight manipulator.

FIG. 32 is a greatly enlarged fragmentary view similar to FIG. 31 andillustrates details of a wheel of the boom support bogie.

FIG. 33 is a somewhat enlarged fragmentary plan view of the tool supportcarriage of the freight manipulator with a shifted and pivoted conditionof the carriage illustrated in phantom.

FIG. 34 is a somewhat enlarged fragmentary side elevational view of thetool support carriage of the freight manipulator with a tilted conditionof a tool support tine illustrated fragmentarily in phantom.

FIG. 35 is a diagrammatic fragmentary longitudinal sectional view at areduced scale and illustrates operational details of the lift cylindermechanism for the tool support carriage.

FIG. 36 is an enlarged fragmentary transverse sectional view taken online 36--36 of FIG. 6 and illustrates details of drive elements andconnections thereof to drive wheels of the freight manipulator.

FIG. 37 is a diagrammatic perspective view illustrating a shift cylindermechanism of the tool support carriage of the freight manipulator.

FIG. 38 is a greatly enlarged transverse sectional view taken on line38--38 of FIG. 15 and illustrates details of a surface engaging wheel ofthe base section of the telescoping conveyor.

FIG. 39 is a diagrammatic fragmentary longitudinal sectional view at anenlarged scale of a modified embodiment of the head section of thetelescoping conveyor with a declinable end portion.

FIG. 40 is a fragmentary perspective view of a second modifiedembodiment of the head section of the telescoping conveyor andillustrates a worker platform therefor in a deployed condition.

FIG. 41 is a fragmentary side elevational view of the second modifiedembodiment of the head section of the telescoping conveyor with theworker platform.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

Referring to the drawings in more detail:

The reference numeral 1 generally designates a mixed freight handlingsystem embodying the present invention. The system 1 generally includesa telescoping or translation conveyor 2, overlapping and communicatingarticles 4 with a fixed conveyor 3, and a freight manipulator 5 whichstraddles the telescoping conveyor 2 and fixed conveyor 3 and whichcommunicates freight 6 with a manipulator or freight conveyor 7. Thetelescoping conveyor 2 is translatable to extend into a truck trailer 8parked at a dock 9 to receive hand liftable articles 4 to convey them tothe fixed conveyor 3 for further handling. The freight manipulator 5 istranslatable to engage manually nonliftable freight 6 in the trailer 8to transfer it to the freight conveyor 7.

Referring to FIGS. 11 and 12, the extendible or telescoping conveyor 2includes a rear base section 14, a middle lift section 15, and a fronthead section 16. The lift section 15 is pivotally connected to the basesection 14, and the head section 16 is pivotally connected to the liftsection 15, both for pivoting about respective axes transverse to alongitudinal extent of the conveyor 2. The head section 16 includes arear pitch frame 18 (FIG. 18) which is pivotally connected to a frontend 19 of the lift section 15 to allow a pitching or inclinedrelationship between the head and lift sections and a front swing frame20 pivotally connected to the pitch frame 18 for pivoting about avertical axis, that is, for swing movements by the head section 16.

A conveyor lift strut assembly 23 (FIGS. 11 and 12) is connected t thelift section 15 and the head section 16 and is operable to raise thehead section 16 to facilitate the manual placement of stacked articles 6thereon. The assembly 23 includes a pair of lift struts 24 pivotallyconnected to the front end 19 of the lift section 15, surface engagingwheels 25 journaled at outer ends of the struts 24, and a pair ofhydraulic lift cylinders 26 pivotally connected between the struts 24and the pitch frame 18 of the head section 16. Leveling links 27 arepivotally connected between the struts 24 and the pitch frame 18. Whenthe cylinders 26 are extended, the struts 24 are pivoted downwardly asthe lift section 15 is inclined. The links 27 pivot the head section 16downwardly in such a manner that it remains substantially horizontalwhen lifted.

Referring to FIGS. 1, 3, and 6, the freight manipulator 5 generallyincludes a mobile chassis 30, an extendible boom or boom assembly 31mounted on the chassis 30, a boom support bogie 32 mounted at a frontend 33 of the boom 31, a tool support carriage assembly 34 mounted atthe front end 33 of the boom 31, and tool receiving tines or forks 35mounted on the tool carriage assembly 34. The boom 31 includes a rearboom section 38 mounted through the chassis 30, a middle boom section 39sleeved within the rear boom section 38, and a front boom section 40sleeved within the middle boom section 39. The boom assembly 31 has alength to allow the forks 35 to reach freight 6 at a front end 42 of atrailer 8 of standard length when the chassis 30 is positioned at itsforwardmost position near the edge 44 of the dock 9 (FIGS. 3 and 4).

FIGS. 4 and 10 illustrate a guide means or guide assembly 48 for thetelescoping conveyor 2 and the freight manipulator 5 of the system 1.Referring to FIG. 10, an elongated guide trench 49 is formed intosurface 50 of the dock 9 to receive the guide assembly 48. A pluralityof cross beams or ties 53 are positioned across the trench 49 at spacedlocations therealong to support the guide assembly 48. Each tie 53 is anI-beam and has a pair of track pads 54 positioned thereon with soundinsulation material 55 sandwiched therebetween. A pair of elongatedparallel conveyor support rails 56 are attached to the ties 53 throughthe pads 54 and material 55 along the length of the trench 49. The rails56 are illustrated as I-beams and statically support the fixed conveyor3 while dynamically supporting the telescoping conveyor 2 on top flanges57. Brackets 58 formed of angle stock are attached to webs the rails 56along their lengths. The fixed conveyor 3 is mounted on inwardlydirected flanges of the brackets 58.

Parallel main rails 60 are mounted on the cross ties 53 through the pads54 and insulation material 55 outside of the conveyor support rails 56.The main rails 60 support and guide the freight manipulator 5 and guidethe telescoping conveyor 2. The rails 60 are similar in cross section toconventional railroad rails and each includes a base flange 61 and a topflange 62 which are connected by a web 63. Top surfaces 64 of the topflanges 62 support wheels 65 and drive wheels 66 of the freightmanipulator 5 (FIG. 6). The main rails 60 have inwardly open channelswhich form conveyor guide tracks 68 for depending guide rollers 69 ofthe base section 14 of the telescoping conveyor 2. The guide rollers 69normally engage upper surfaces 75 of the base flanges 61.

Outwardly open channels of the rails 60 form safety tracks 73 foranti-tipping or stabilizing rollers 74 associated with the wheels 65 ofthe freight manipulator 5 to resist forward tipping of the manipulatorchassis 30 caused by moments on the front end 34 of the boom 31, such asmight be caused by extension of the tool carriage 34 into a trailer 8with a bed 77 considerably lower than the dock surface 50. Theanti-tipping rollers 74 normally ride loosely on upper surfaces 75 ofthe base flanges 61, with weight of the manipulator chassis 30 borne bythe upper surfaces 64 of the rails 60. Should a chassis tipping momentoccur, the rollers 74 engage lower surfaces 76 of the top flanges 62 toresist such tipping.

FIGS. 5 and 10 illustrate structural and operating details of the fixedconveyor 3. The conveyor 3 includes a fixed conveyor frame 80 whichsupports a fixed conveyor belt 81 and a fixed conveyor belt drivemechanism 82 which drives the belt 81. The frame 80 includes elongatedside members 84 connected by a belt slide sheet 85 and cross members 86.The frame 80 is supported along the trench 49 by the brackets 58 on theconveyor support rails 56. The drive mechanism 82 includes a drive frame88 attached to the fixed conveyor frame 80 and depending therefrom intoa fixed conveyor drive pit 89 formed in the dock 9 and communicatingwith the trench 49. The drive mechanism 82 includes a fixed conveyorbelt motor 90 mounted on the drive frame 88 and connected by an endlesssprocket chain 91 to a belt drive roller 92. An upper flight of thefixed conveyor belt 81 extends between front and rear end rollers 94 and95 and is supported by the slide sheet 85. Within the frame 80, the belt81 is threaded over idler rollers 96 and about the tension rollers 97and the drive roller 92.

Referring to FIGS. 10, 11, 15, and 21, the base section 14 of thetelescoping conveyor 2 includes a base section frame 100 formed of sidemembers 101 connected by cross members 102 which additionally support abase section conveyor belt slide sheet 103. The base section 14 issupported on the conveyor support rails 56 by wheels 104 mounted on theside members 101 (FIGS. 11 and 38). At least one of the wheels is adrive wheel 105 drivingly engaged with a base section translation motor106 through a drive belt 107. The motor 106, belt 107, and drive wheel105 form a translation mechanism or motor means 108 for the telescopingconveyor 2. The base section 14, and the telescoping conveyor 2 ingeneral, are guided by engagement of the guide rollers 69 with theconveyor guide tracks 68 of the main rails 60. The guide rollers 69 arejournaled on depending legs 109 which are attached to the side members101. An upper flight of a base section conveyor belt 112 extends betweenfront and rear rollers 113 and 114 and is supported by the slide sheet103. The belt 112 is supported within the base section frame 100 byidler rollers 115 and at least one tension roller 116. In theillustrated base section 14, the rear end roller 114 is a drive rollerand is drivingly engaged with a conveyor belt drive motor 117 throughand endless sprocket chain 118. Preferably, a rear end 119 of the basesection frame 100 is provided with means to ease the transition ofarticles 4 therefrom to the fixed conveyor belt 81. As illustrated inFIGS. 1 and 3, the base section 14 may be provided with an article ramp120 down which articles 4 slide from the base section belt 112 to thefixed conveyor belt 81.

FIGS. 12, 16, and 20 illustrate details of the lift section 15 of thetelescoping conveyor 2. The lift section 15 includes a lift sectionframe 125 formed of a pair of elongated parallel side members 126connected by cross members 127 which support a lift section conveyorbelt slide sheet 128. The lift section 15 does not have wheels thereonwhich directly engage the rails 56 but is supported by its connection tothe base section 14, the head section 16, and the lift strut assembly 23which rides on the rails 56. Referring to FIG. 17, the side members 126of the lift section 15 have pivot ears 129 which extend therefrom at arear end 130 of the lift section frame 125 and are received in the sidemembers 101 at a front end 131 of the base section 14. Aligned pivotpins 132 extend through the respective front ends of the base sectionside members 101 and the pivot ears 129 to form a transverse pivot axisbetween the base section frame 100 and the lift section frame 125. Thepivotal joint between the base section 14 and lift section 15 is adaptedto allow inclining of the lift section frame 125 upwardly relative tothe horizontal base section frame 100. The front end 19 of the liftsection frame 125 is pivotally connected to the head section 16, as willbe detailed below, whereby the lift section 15 is suspended between thebase section 14 and the lift strut assembly 23 when inclined.

An upper flight of a lift section conveyor belt 135 extends betweenfront and rear end rollers 136 and 137 and is supported therebetween bythe slide sheet 128. Within the lift section frame 125, the belt 135passes around a tension roller 138 and a drive roller 139. The belt 135is propelled by a motor 140 engaged through a drive belt 141 with thedrive roller 139. A front end portion 142 of the belt 135 is declined,for reasons described below. The front portion 142 passes around anupper direction changing roller 143, is supported by a declined slidesheet 144, passes around the front end roller 136, and passes about alower direction changing idler roller 145. The front end roller 136 issupported on arms 146 which extend forward of the front end 19 of thelift section frame 125. Depending ears 147 (FIG. 20) are provided onlower sides of the side members 126 at the front end 19 and have thestruts 24 of the lift strut assembly 23 pivotally connected thereto.

FIGS. 11-14, 18, 19, 22, and 23 illustrate details of the head section16 of the telescoping conveyor 2. The head section 16 includes the pitchframe 18, which is pivotally connected to the front end 19 of the liftframe 15 and has the lift strut assembly 23 pivotally connected thereto,and the swing frame 20 which is pivotally connected to the pitch frame18 by a swing or swivel joint 150 (FIG. 18) for swinging of the swingframe 20 about a vertical axis. The pitch frame 18 includes a crossplate 151 with rearwardly extending double side ears 152 attachedthereto. Referring to FIGS. 19 and 23, the side ears 152 are pivotallyconnected to a forwardly extending ear 153 on the front end 19 of thelift section frame 125. Aligned transverse pivot pins 154 extend throughthe ears 152 and 153 to provide for pitching or pivoting of the pitchframe 18 about a transverse axis in a downward direction relative to thelift section 15 (clockwise as viewed in FIG. 12).

Rearwardly extending lugs 155 are positioned at a lower end of the crossplate 151 at the outer edges thereof and have the leveling links 27pivotally connected thereto. The upper ends of the lift cylinders 26 arepivotally connected to a front upper side of the cross plate 151. Alonga vertical center line of the cross plate 151, forwardly extending swingjoint ears 156 are provided. The ears 156 have vertically alignedapertures 157 therethrough.

The swing frame 20 includes side members 160 connected by a main crossmember 161 (FIGS. 18 and 23) and additional cross members 162. A centralspinal beam 163 extends rearwardly from the main cross member 161 andsupports a vertical swing joint shaft 164 which is journaled through theapertures 157 of the swing joint ears 156. On each side of the spine163, sets of front pivot webs 165 are attached to the spine 163 and themain cross member 161, and rear pivot webs 166 are attached to the frontside of the cross plate 151. Right and left swing cylinders 167 arepivotally connected between the respective sets of front and rear pivotwebs 165 and 166. The swing cylinders 167 are extended and retracted ina coordinated manner to pivot the swing frame 20 about the swing shaft164. It is desirable to limit the degree of swing of the frame 20 toavoid collisions between the swing frame 20 and the lift cylinders 26and between a front end 169 of the swing frame 20 and the side walls 170(FIG. 1) of the trailer 8. A limit switch assembly 171 (FIG. 13) ispositioned on the spine 163, with portions also mounted on the crossplate 151, and connected to controls (not shown) for the swing cylinders167. FIG. 14 diagrammatically illustrates the maximum degree of swing ofthe swing frame 20 relative to the pitch frame 18 of the head section16.

The illustrated head section 16 is provided with a rear conveyor belt175 and a front conveyor belt 176. The rear belt 175 extends between afront drive roller 177 and a rear idler roller 178 over a slide sheet179 (FIG. 18). Beneath the slide sheet 179, the rear belt 175 issupported by additional idler rollers 180 and a tension roller 181. Thefront belt 176 extends between a rear drive roller 184 and a front idlerroller 185 over a slide sheet 186 (FIG. 18). The front belt 176 issupported by and passes about additional idler rollers 187 and at leastone tension roller 188. The front and rear belts 176 and 175 arepropelled by a common motor 189 which is engaged with the rear driveroller of the front belt 176 through a belt or sprocket chain 190. Onthe opposite side of the swing frame 20 from the motor 189, a belt orsprocket chain 191 is engaged between the drive roller 184 of the frontbelt 176 and the drive roller 177 of the rear belt 175, whereby thebelts 175 and 176 are driven in unison.

As shown particularly in FIG. 18, the rear end idler roller 178 of therear belt 175 is spaced above the declined section 142 of the liftsection belt 135. The declination of the belt section 142 and theunderlapping of it in relation to the end idler roller 178 accommodatesthe swinging of roller 178 thereabove while maintaining an overlappingrelationship of the belt 175 with the front section 142 such that anarticle 4 can be passed from the belt 175 of the head section 16 to thebelt 135 of the lift section 15. The conveyor belts 112, 135, 175, and176 form an article support surface 182 (FIG. 1) which is capable ofsimultaneously supporting a moving succession of articles 4.

FIGS. 6, and 24-37 illustrate details of the freight manipulator 5.Referring to FIGS. 25 and 36, the manipulator chassis 30 is formed ofside members 200 connected by cross members 201 and end panels 202 toform a rigid chassis frame 203. Lower portions of the side members 200have legs 204 attached thereto on which the wheels 65 and drive wheels66 are journaled. The wheels 65 and 66 are rimmed wheels, similar torailroad type wheels, such that the chassis is essentially self guiding.Boom support brackets 205 are mounted above the cross members 201 andhave the rear boom section 38 mounted therethrough. The chassis is selfpropelled by means of a chassis translation motor 208 (FIG. 6) engagedwith the drive wheels 66 through sprocket chains 209. Drive istransferred from the motor 208 to both drive wheels 66 through a clutchmechanism 210 and a drive shaft 211 (FIG. 36) mounted across the chassisframe 203 in pillow blocks 212 positioned on brackets 213. The shaft 211has sprockets thereon which engage the chains 209. As illustrated inFIG. 36, a lower edge 214 of the end panels 202 and inner surfaces 215of the side members 200 form an opening or tunnel 216 through thechassis 30 through which articles 4 on the telescoping conveyor 2 or 3can pass. All operating components of the chassis 30 are positionedoutside of the boundaries of the tunnel 216 to avoid interference witharticles 4 on the conveyors 2 and 3.

Referring particularly to FIGS. 27 and 28, the rear boom section 38 issupported by and extends through the chassis 30. The rear boom section38 has a front roller 220 on which the middle boom section 39 issupported and rides during extension and retraction of the boom 31. Themiddle boom section 39 has a rear roller 221 which bears against andrides along an under side of an upper wall of the rear boom section 38.The front boom section 40 is supported within the middle boom section 39on a front roller 222 and by engagement of a rear roller 223 mounted ata rear end of the front section 40 with an under side of an upper wallof the middle boom section 39. A rear portion 225 of the middle boomsection 39 extends through a rear end panel 202 of the chassis 30.

The middle boom section 39 is extended from and retracted into the rearboom section 38 by operation of a pair of middle section hydrauliccylinders 227 having rear ends thereof connected to the rear boomsection 38. The cylinders 227 are a type of hydraulic cylinders in whicha rod 228 thereof extends entirely through the cylinder and out each ofthe ends thereof. A piston (not shown) is positioned on the rod 228 at amidpoint thereof and seals between the rod 228 and cylinder 227. A frontend 229 of each of the rods 228 is connected to the front end of themiddle boom section 39, and a rear end 230 of the rod 228 extendsthrough the rear panel 202 of the chassis frame 203. When the middleboom section 39 is to be extended, the front ends 229 of the rods 228are extended out of the cylinders 227 while the rear ends 230 areretracted into the cylinders 227.

The front boom section 40 is extended from and retracted into the middleboom section 39 by operation of a front section hydraulic cylinder 232similar to the middle cylinders 227. The front cylinder 232 has a rod233 extending therethrough and having a rear end 234 connected to a rearend of the middle boom section 39, and a front end 235 of the rod 233extends out of a front end of the cylinder 232. The front cylinder 232is connected to a rear end of the front boom section 40 by pins 236.When the front boom section 40 is to be extended, the rear end 234 ofthe rod 233 is extended out the rear end of the cylinder 232 while thefront end 235 is retracted thereinto to urge the front boom section 40forward.

Although the boom assembly 31 is described and illustrated as havingthree telescoping sections, it could alternatively have a greater orlesser number of sections or be of fixed length. While the extendibleboom 31 has greater flexibility of use than a fixed boom assembly and ismore compact when retracted, costs can be reduced somewhat with a boomof fixed length. A fixed length boom would be useful particularly at adock at which only short trailers, known as "pup" trailers, are to beloaded and unloaded. With a fixed length boom, extension of the tools 35into the trailer 8 is accomplished entirely by operation of the chassismotor 206.

FIGS. 30-32 illustrate details of the boom support bogie assembly 32.The bogie 32 includes a pair of L-shaped legs 240 connected by a crossbrace 241 and pivotally connected to the front end 33 of the boomassembly 31 by a bogie pivot shaft 242. Bogie wheels 243 are journaledat lower ends of the legs 240 and ride on the main support rails 60 onthe dock 9 and on the bed 77 of the trailer 8 when the boom 31 isextended thereinto. The bogie assembly 32 is made pivotal to accommodatelevel differences between the surface 50 of the dock 9 and the bed 77 ofthe trailer 8. A hydraulic cylinder 244 is connected between a lowerside of the front end of the front boom section 40 and the cross brace241. The cylinder 244 is extended or retracted to respectively lower orraise the level of the wheels 243 with respect to the front end 33 ofthe boom 31. A lower side 245 of the cross brace 241 and inner sides 246of the legs 240 define a bogie tunnel 247 which is sized similar to andaligned with the tunnel 216 of the chassis 30 and is provided for thesame purpose. The bogie assembly 32 supports the weight of the front end33 of boom assembly 31, the tool carriage assembly 34, and any freight 6carried thereby.

FIGS. 33-35 and 37 illustrate details of the tool support carriageassembly 34. The carriage assembly 34 includes a tool carriagearticulation system 250 by which the freight engagement tools 35 aremoved with respect to the front end 33 of the boom assembly 31. Thearticulation system 250 generally includes a transverse tool carriageshift mechanism 251, a tool carriage pivot mechanism 252, and a toolcarriage lift mechanism 253.

The tool carriage shift mechanism 251 includes a shift frame 255 mountedon the front end 33 of the boom assembly 31 and including a transverselyextending carriage shift support beam 256 attached at a lower region ofthe front end 33. The beam 256 is illustrated as an I-beam withdepending ribs from a lower flange thereof forming a lower shift track257. An upper shift track 258 is formed by an upwardly open channelshaped member extending across the front end 33 parallel to the lowertrack 257. A tool shift carriage 259 rides on the lower track 257 andupper track 258 and, additionally, on a middle shift track 260 formed bythe upper surface of the lower flange of the support beam 256. The shiftcarriage 259 includes a lower plate 261 which supports a set of lowerrollers 262 which ride in the lower shift track 257 and an upper plate263 which supports a set of upper rollers 264 which ride in the uppertrack 258. A middle plate 265 supports middle rollers 266 which ride onthe middle track 260. The middle track 260 bears most of the weight ofthe shift carriage 259, while the upper and lower tracks 258 and 257provide static and dynamic cantilever support to the shift carriage 259.

FIG. 37 diagrammatically illustrates the operation of a shift cylinder269 which moves the shift carriage relative to the shift frame 255. Thecylinder 269 has a rod 270 extending entirely therethrough with ends ofthe rod 270 being oriented parallel to the shift tracks 257, 258, and260 and attached to the shift frame 255 whereby the cylinder 269 istranslatable along the rod 270. The cylinder 269 has front and rear setsof right and left shift pulleys, 271 and 272 respectively, journaledthereon. The pulleys 271 and 272 have respective right and left shiftcables 273 and 274 passing therearound with one end attached to theshift frame 255 and the other end attached to a shift plate 275 attachedto the shift carriage 259. The right and left cables 273 and 274 arwrapped in opposite directions about their respective pulleys 271 and272. The purpose of the arrangement illustrated in FIG. 37 is to doublethe amount of translation of the shift carriage 259 for a given lengthof stroke of the shift cylinder 269. Thus, when the cylinder 269 istranslated a given distance to the left, the arrangement of the leftshift pulleys 272 and cables 274 cause the shift carriage 259 to shiftto the left a distance twice the length of movement of the shiftcylinder 269.

The shift carriage 259 has a tool pivot carriage or frame 280 pivotallyconnected thereto at an outer end thereof for pivoting about a verticalaxis. The pivot carriage 280 has upper and lower pivot shaft supportplates 281 and 282 respectively extending rearwardly therefrom whichform cross members for the tool pivot carriage 280. The plates 281 and282 support a tool pivot shaft 283 which passes through upper and lowerpivot bearings 284 and 285 at the outer end of the tool shift carriage259. Left and right pivot cylinders 286 and 287 are connected to a rearend of the shift carriage 259 and have respective rods 288 and 289connected to opposite ends of a pair of sprocket chains 290 which engagesprockets on the pivot shaft 283. The cylinders 286 and 287 are operatedin cooperation to pivot the pivot carriage 280 to the left and right. Asshown in FIG. 24, the pivot carriage 280 can be pivoted through 180degrees from left to right.

The tool carriage lift mechanism 253 is a two stage lift arrangement.Referring to FIGS. 33-35, the pivot carriage 280 has a pair of rails 295connected to the upper and lower cross members 281 and 282 which forminwardly open fixed tracks. An intermediate lift carriage 296 hasintermediate rollers 297 thereon which ride in the fixed lift tracks295. The intermediate carriage 296 is connected by an intermediate liftcylinder 298 to the upper plate 281 of the pivot carriage 280. Theintermediate carriage 296 has a tool lift cylinder 299 connected theretowhich is also connected to a tool support carriage 300 on which theforks or tines 35 are mounted. As shown in FIGS. 33 and 35, a piston rod303 of the tool lift cylinder 299 has a pair of pulleys 304 positionedat an end thereof. Cables 305 are connected to the intermediate liftcarriage 296, pass over the pulleys 304, and connect to the tool supportcarriage 300. When the cylinder 299 is extended a given stroke length,the tool support carriage 300 is lifted by a distance double the strokelength in a manner similar to that illustrated in FIG. 37 for theconnection of the shift cylinder 269 to the shift carriage 259.

When the intermediate lift cylinder 298 and the tool lift cylinder 299are both retracted, the tool support carriage 300 is in such a positionthat the tools 35 are spaced off the surface 50 of the dock 9. In such aposition, all portions of the tool support carriage assembly 34 arepositioned above the telescoping conveyor 2 and the fixed conveyor 3 toavoid interference with articles 4 travelling therealong. When it isdesired to engage freight 6 at dock level or on the bed 77 of thetrailer 8, the intermediate lift cylinder 298 is extended to lower theintermediate carriage 296 to dock level. The tool support carriage 300is supported on the carriage 296 and is, thus, lowered therewith as arethe tools 35. The intermediate cylinder 298 is retracted to lift thefreight 6 for transfer thereof. If a load of freight 6 is stacked onanother one, the tools 35 may be raised from their normal positions toreach the freight by extending the tool lift cylinder 299 to raise thetool support carriage 300 relative to the intermediate lift carriage296.

The tools or tines 35 are pivotally mounted on a tool support shaft 306extending across the tool support carriage 300. Lower ends of the tools35 are engaged by tool tilt cylinders 307 which are operable to tilt thetools 35 upwardly and downwardly to a slight degree to facilitateengagement and disengagement with the freight 6.

The articulation system 250 allows great flexibility in positioning thetools 35 to engage freight 6 in the trailer 8 and to disengage it ontothe freight conveyor 7. The shift mechanism 251 allows freight 6positioned at the side walls 170 of the trailer 8 to be engaged andlifted. Additionally the shift mechanism 251 cooperates with the pivotmechanism 252 to allow freight 6 to be turned and deposited onto thefreight conveyor 7. The tilting capability of the tools 35 allowsfreight 6 to be carried more securely by tilting the tools upwardly aslight amount while downward tilting of the tools facilitates thewithdrawal of the tools from the freight.

Referring to FIGS. 6 and 26, the freight manipulator 5 only requiresexternal electrical power for operation. An electrically drivenhydraulic pump 308 and hydraulic reservoir 309 provide hydraulicpressure to drive the hydraulic motors and cylinders on the manipulator5. The manipulator chassis translation motor 206, the boom extension andretraction cylinders 227 and 233, the shift cylinder 269, the pivotcylinders 286 and 287, the lift cylinders 298 and 299, and the tiltcylinders 307 are all driven by fluid from the hydraulic pump 308 ascontrolled by a manipulator computer 310 by way of a system of hydraulicvalves 311.

Electrical power for the pump 308 is communicated to the manipulator 5by a power rail 312 (FIGS. 1 and 2) supported above the dock 9. Althoughnot illustrated in detail, the power rail 312 has a plurality of barepower conductors extending therealong which are contacted by shoes on atrolley 313 which is mechanically connected to a collector arm 314 onthe manipulator chassis 30. The contact shoes are connected toconductors of a power cable which supplies electrical power to thehydraulic pump 308. The trolley 313 is dragged along the power rail 312as the manipulator 5 is translated along the tracks 60. Additionally, acommunication cable 315 is supported by the power rail 312. Thecommunication cable 315 is festooned along the lower side of the rail312, that is, looped through hangers 316 which are slid along the rail312 as the manipulator 5 is translated. In FIG. 1 only one power rail312 is illustrated for graphic convenience. However, each freightmanipulator 5 has a power rail 312 associated therewith.

Referring to FIG. 26, the freight manipulator 5 is provided with a takeup mechanism 320 for paying out and taking up hydraulic hoses leading tothe hydraulic cylinders which are moved when the boom assembly 31 isextended. The mechanism 320 includes a take up bracket 321 mounted onthe chassis frame 203 and has a plurality of hose reels 322 rotatablymounted thereon. The hoses 323 supplying the movable hydraulic cylindersare wrapped onto the reels 322. Supply hoses (not shown) from thehydraulic pump 308 are connected by rotating connections (not shown) inthe centers of the reels 322. As the boom assembly 31 is extended, thereels 322 rotate to pay out the hoses 323. The reels 322 are preferablyspring loaded so that they rotate in an opposite direction to take u thehoses 322 as the boom 31 is retracted.

The telescoping conveyor translation and lift motors are hydraulicallyoperated and pay out and retract hoses therefor in a manner similar tothe take up system 320. Referring to FIG. 6, a plurality of hoses reels324 are mounted in the pit 89 in which the drive mechanism 82 for thefixed conveyor 3 is mounted. Hydraulic hoses 325 are wrapped on thereels 324 and are connected to a fitting (not shown) in the base section14 of the telescoping conveyor 2. As the conveyor 2 is translated towardthe trailer 8, the reels 324 pay out the hoses 325 which slip along theconveyor support rails 56 behind the base section 14. The reels 324 arespring loaded so that as the conveyor 2 is retracted from the trailer 8,the hoses 325 are taken up by the reels 324. The telescoping conveyor 2also has a communication cable not shown) connected to and controllinghydraulic valves (not shown) which, in turn, control the hydraulicmotors and cylinders within the conveyor 2. The communication cable ispayed out and taken up in the same manner as the hydraulic hoses 325.

The tool support carriage 300 is preferably adapted for interchangeablyattaching a variety of freight engaging tools to the tines 35 forengaging and unloading various types of freight 6. As illustrated inFIG. 1, a tool rack 327 has a variety of types of tools positionedthereon, such as a jib boom (not shown), a set of drum clamps 328, forkextensions 329, and the like. A manipulator 5 illustrated near the rack327 has a rug pole 330 mounted thereon. Preferably, the special tools328-330 are receivable onto the tool support carriage 300 by insertionof the tines 35 thereinto. The attachment of the tools 328-330 isfacilitated particularly by the shift mechanism 251 and the tiltcylinders 307.

The freight manipulator 5 is adapted for execution of a number offunctions automatically. Such functions could include the retraction ofthe boom 31 and translation of manipulator 5 and coordinated operationof the articulation system 250 to place a load of freight 6 onto thefreight conveyor 7 after engaging such a load, and thereafterwithdrawing to a parking position or returning to the trailer 8 foranother load. Additionally, the interchange of tools could be automated.Such automated functions are made possible by programming of themanipulator control computer 310 to sequence the hydraulic valves 311 inthe proper order and for the necessary duration for the desiredfunction.

FIG. 39 illustrates a modified embodiment of a head section 335 for thetelescoping conveyor 2. In the modified head section 335, a front endportion of a conveyor belt 336 thereof is declinable. The belt 336passes about upper and lower direction rollers 337 and 338 to an endidler roller 339. The end roller 339 is supported between end arms 340which are pivotally connected to side members 341 of the head section335. An extendible member (not shown) may be connected between the arms340 and the side members 341 for selectively declining and leveling thearms 340. The modified head section 335 is particularly useful inreceiving articles 4 which are positioned on the bed 77 of a trailer 8to reduce the amount of lift necessary to place the articles onto thehead section 335. In other respects, the head section 335 is similar tothe head section 16 described above.

FIGS. 40 and 41 illustrate a second modified embodiment of a headsection 345 which is provided with a collapsible worker platform 346assembly. A platform member 347 has rearwardly extending arms 348 whichare pivotally connected at front ends thereof to hanger members 349which are pivotally connected to a head section frame 350. Rear ends ofthe arms 348 are pivotally connected to control levers 351 which arealso pivotally connected to the side members 350 to form a parallelogramlinkage arrangement. Cross braces may interconnect the control levers351 and the arms 348. An extendible cylinder 352 is pivotally connectedbetween one of the control levers 351 and one of the side members 350.Extension of the cylinder 352 deploys the platform assembly 346 whileretraction collapses the assembly 346 beneath the head section 345. Theworker platform assembly 346 is useful for lifting a worker to reacharticles 4 stacked to a height would otherwise be difficult to transferonto the head section 345. In other respects, the head section 345 issubstantially similar to the head section 16 described above.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. An article handling conveyor system for transferringarticles between spaced apart first and second locations, said secondlocation being within an elongated article transferring vehicle and saidfirst location being external to said vehicle, said systemcomprising:(a) an elongated fixed conveyor positioned at said firstlocation; (b) an elongated movable conveyor positioned at said firstlocation in a straddled vertically spaced parallel relation to saidfixed conveyor to communicate articles therewith and movable between aretracted condition at said first location and an extended conditioninvading said second location while maintaining a portion of saidmovable conveyor in said straddled vertically spaced parallel relationto said fixed conveyor; (c) each of said conveyors including meansforming respective support surfaces capable of supporting respectivemoving successions of articles; (d) said movable conveyor including asubstantially horizontal base section; and (e) said movable conveyorincluding a lift section pivotally connected to said base section at anend thereof toward said second location, said lift section beingselectively inclined upwardly in said extended condition of said movableconveyor.
 2. A system as set forth in claim 1 wherein said movableconveyor includes:(a) a head section pivotally connected to said liftsection and lifted when said lift section is inclined, said head sectionbeing interrelated to said lift section in such a manner that said headsection is maintained substantially horizontal when said lift section isinclined.
 3. A system as set forth in claim 2 wherein:(a) said headsection is selectively pivotable about a vertical axis.
 4. A system asset forth in claim 2 and including:(a) conveyor lift means pivotallyconnected to an end of said lift section toward said other location andto said head section, said carriage means being operable to incline saidlift section of said movable conveyor.
 5. A system as set forth in claim2 and including:(a) a lift carriage pivotally connected to said liftsection and extending beneath said head section; (b) a linear lift motorpivotally connected between said lift carriage and said head section;and (c) a leveling link pivotally connected between said lift carriageand said head section and operative to maintain said head sectionsubstantially horizontal as said lift motor is operated to incline saidlift section.
 6. A system as set forth in claim 2 and including:(a) aworker platform connected to said head section at an end thereof towardsaid other location to support a worker when said base section islifted.
 7. A system as set forth in claim 6 wherein:(a) said platform iscollapsible under said base section when said base section is notlifted.
 8. A system as set forth in claim 1 and including:(a) conveyorguide means extending from said first location part way to said secondlocation and having said movable conveyor engaged therewith, at leastpart of said movable conveyor engaging said guide means in said extendedcondition of said movable conveyor.
 9. A system as set forth in claim 1and including:(a) a conveyor support rail extending from said firstlocation part way to said second location and having said movableconveyor supported thereon, at least part of said movable conveyor beingsupported by said rail in said extended condition of said movableconveyor.
 10. A system as set forth in claim 1 and including:(a) a pairof conveyor support rails extending from said first location part way tosaid second location and having said movable conveyor supported thereon;(b) a pair conveyor guide tracks extending parallel to said rails fromsaid first location part way to said second location and having saidmovable conveyor engaged therewith; and (c) at least part of saidmovable conveyor being supported by said rails and engaging said tracksin said extended condition of said movable conveyor.
 11. A method fortransferring articles between spaced apart first and second locations,said second location being within an elongated article transferringvehicle and said first location being external to said vehicle, saidsystem comprising the steps of:(a) positioning an elongated fixedconveyor at said first location, said fixed conveyor including meansforming a first support surface capable of simultaneously supporting amoving succession of articles; (b) positioning an elongated movableconveyor at said first location in a straddled vertically spacedparallel relation to said fixed conveyor to communicate articles withsaid fixed conveyor, said movable conveyor including means forming asecond support surface capable of simultaneously supporting a movingsuccession of articles, and said movable conveyor including a basesection and a lift section which is raisable with respect to said basesection; (c) moving said movable conveyor between a retracted conditionat said first location and an extended condition invading said secondlocation while maintaining said movable conveyor in said straddledvertically spaced parallel relation to said fixed conveyor; (d)selectively raising said lift section with respect to said base sectionwhen said movable conveyor is in said extended condition; (e)communicating an article between said head section and said basesection; and (f) conveying said article along said movable conveyor insaid extended condition thereof.
 12. A method as set forth in claim 11wherein an inclinable lift section connects said head section to saidbase section and including the steps of:(a) inclining said lift sectionto raise said head section; and (b) communicating said articles betweensaid head section and said base section by way of said lift section. 13.A method as set forth in claim 11 wherein said head section is angularlyswingable with respect to said base section about a vertical axis andincluding the step of:(a) swinging said head section through a selectedangle with respect to said base section with said movable conveyor insaid extended condition.
 14. A method as set forth in claim 11 andincluding the step of:(a) guiding said movable conveyor during saidmoving by conveyor guide means extending from said first location partway toward said second location.